Bicycle frame



FIG. 1 is a side elevational view of a bicycle frame showing our new design;

FIG. 2 is a rear perspective view thereof; and,

FIG. 3 is a front elevation view thereof.

The broken lines shown in FIGS. 1, 2 and 3 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a bicycle frame, as shown and described. 